Abrasive bodies and grinding tools of this type are known and are for example used for processing metal or wood, for manufacturing prostheses or for the podiatry or manicure. As during grinding processes temporarily and locally a high heat loading can be produced, it is repeatedly necessary, to interrupt the grinding process, to cool the abrasive body and the to be processed areas. Furthermore, it is known, to cool the abrasive body during the grinding process, to prevent pain caused by heat in the patient or to prevent heat damages on the to be worked workpiece.
A grinding tool of the above mentioned type is for example described in DE 20 2007 012 818 U1. The grinding tool known from this printed document, is used in the field of podiatry and has a cap-like abrasive body. The abrasive body consists of a metal substrate layer, on which an abrasive layer is applied. Furthermore, a driving device for the rotational driving of the abrasive cap belongs to the grinding tool, wherein the driving device and the abrasive cap are connected to each other via a clamping shaft. To cool the abrasive body during the grinding process, cooling bores are provided in the abrasive body, via which cooling air flows to the to be treated area from the inside.
It is seen to be a disadvantage, that the cooling, especially during longer treatments, cannot completely discharge the grinding heat, so that local heat damages can be produced. To prevent this, a podiatrist is instructed by a patient when the heat makes the treatment unpleasant. However, the risk of causing burns exists during the treatment, that is especially high with diabetics, whose temperature sensation at the feet is often poor.
From DE 20 2009 006 069 U1 a polishing disc is known that is made from polyurethane foam. The soft polishing disc has thermochromic colouring agents, to indicate optically to a user by means of colour change that the polishing disc is getting hot and consequently can damage the paintwork. The thermochromic colouring agents are enclosed in micro-capsules, which during the manufacture of the polishing disc are added to the flexible foam. The micro-capsules further contain a thermoset resin melting at low temperature and an activator bond. To be able to visually see during the polishing process temperature increases which are damaging the paint work, the thermochromic colouring agent changes its colour at a defined colour change temperature. The thermoset resin, melting at a low temperature, has in the area of this colour change temperature its melting range, so that by means of the melting of the resin, the thermochromic colouring agent reacts with the activator bond.
It is seen to be disadvantageous, that the thermoset resin has to initially melt, before the thermochromic colouring agent changes colour. Furthermore, the manufacture of the polishing disc is cumbersome, as the thermochromic colouring agents have to be enclosed together with the activator bond and the thermoset resin in micro-capsules, to mix these followingly to the flexible foam. Furthermore, it is disadvantageous, that with the soft foam no chipping or cutting processing steps can be carried out on the surfaces of the to be processed materials.